This disclosure relates generally to optical signals, and in particular but not exclusively, relates to optical signals for free space optical communication systems.
Current laser transmitters in free space laser communication systems are limited to point-to-point broadcast systems. These point-to-point broadcast systems have pointing, tracking, and alignment issues.
Different developmental efforts aimed at increasing the performance of laser transmitters have emerged. The drawback with the various transmitters developed is that they are employed only in point-to-point broadcast.
Some researchers have used several discrete lasers and fiber links to connect multiple customers. Others have utilized tunable lasers that cannot operate simultaneously at different wavelengths. The problem with these schemes is that the system becomes bulky, expensive, and difficult to maintain. Besides, the basic challenges of point-to-point broadcast remain unsolved.
One of these challenges is the non-uniform intensity of the beam with its Gaussian distribution. The problem with the non-uniform intensity of the Gaussian beam is that it can cause signal loss to receivers not placed within the peak area of the beam. Stated in another way, receivers that receive the portion of the optical signals having the lower intensity along the fringes of the Gaussian distribution are more likely to experience signal loss or errors, as compared to receivers that receive the portion of the optical signal near the center or highest intensity of the Gaussian distribution.
One aspect of the invention includes creating a uniform intensity flat-top beam from a non-uniform intensity optical beam, and canceling a divergence and correcting a phase of the uniform intensity flat-top beam that is created.